Device for moving a beam of light in a plane of impact

ABSTRACT

A device for steady-state adjustment of a light beam enabling laser treatment in an impact plane including a joint enabling rotational movement about one axis and tilting movement about another axis extending perpendicularly to the one axis. The joint is biased to a predetermined position and a mirror is mounted on the joint with first and second magnet-coil arrangments being separately mounted on the joint for respectively enabling independent tilting movement of the joint and the mirror about the one axis and independent rotational movement of the joint and the mirror about another axis. A control unit is provided for controlling current flow in coils of the first and second magnet-coil arrangements to effect movement of the joint and the mirror, whereby the mirror is adjusted to enable deflection of light beam to an impact point in the impact plane.

BACKGROUND OF THE INVENTION

The present invention relates to a device for moving a beam of light ina plane of impact.

STATE OF THE ART

Devices of this type are needed, by way of illustration, in so-calledlaser coagulators such as are employed in ophthalmology. Furthermore,there are, of course, numerous other possible applications in variousfields of technology for such devices, for example, in laser welding.

A device as described herein is, for example, the so-called"micromanipulator" developed by the present applicant. In said prior artdevice, a mirror deflecting the laser beam toward the eye, is movedpneumatically. Said mirror may, for example, be one of the mirrorsdeflecting the operation and/or target beam in the device described inWO 85/00966 or the one described in DE-GM 7 225 429.

This prior art device is--as was recognized in accordance with thepresent invention--not optimum in some instances due to the fact thatthe mirror is moved pneumatically:

The known micromanipulator cannot be readily operated and/or programmedby remote control via a suitable electronic system. The response time ofthe manipulator may, under circumstances, be "noticeable" during theoperation. Furthermore, the manipulation operation is not alwaysnoiseless.

DESCRIPTION OF THE INVENTION

The object of the present invention is to provide a device for moving abeam of light in a plane of impact permitting quick, precise andelectronically controlled manipulation of a beam in a plane of impact.

One solution of the object is successful by still proceeding from adevice in which a mirror, which deflects a beam of light, is tilted orrotated. An inventive element is that said mirror is fixed to atilting/rotating joint, which is biased, by means of a bias device, to ahome position and is connected to magnets. Said magnets are in amagnetic field created by current-carrying coils. By varying the currentflowing through the coils and thus the created magnetic field, it ispossible to tilt the tilting/rotating joint and thereby the mirror in adefined manner. The point of impact of the light beam in the plane ofimpact is moved in a defined manner corresponding to the definedtilting. The invented device has a number of advantages:

The tilting of the mirror and thus the moving of the beam of light inthe plane of impact occurs quickly and noiselessly. The system has adefined home position, in which, for example, the laser beam is directedexactly at the geometric center of the field, over which the laser beammay be moved. On the other hand, with a device control unit, forexample, an electronic control, it is possible to convey the system intoany desired home position with a constant current. In any case, however,it is possible to manipulate the light beam in the plane of impact asthe biased tilting/rotating joint is supported in bearings withpractically no backlash.

In accordance with the present invention, the mirror can be rotatedabout one axis and tilted about another axis, which are perpendicular toeach other, and rotating and tilting the mirror about each of these axesensues by means of a respective coil/magnetic unit, permits the simplestx/y-moving of the point of impact of the light beam in the plane ofimpact.

By means of the "symmetrically rotating" feature of of the presentinvention, tilting moments, which might reduce the precision of theadjustment, are effectively reduced.

The circuit arrangement of the present invention increases the symmetryof the invented device and thereby reduces the danger of the occurrenceof tilt moments.

By reversing the currents flowing through the coils, the mirror may betilted or rotated in both directions even in a symmetrical arrangement.

Various possible bias devices are utilized, which bias the device to itshome position.

The invented device may also be regulated by hand, by means of a controlstick as well as by a control unit.

The control unit permits a programmed moving of the point of impact ofthe light beam or, for example, moving controlled by a image processingdevice. Hereby, the rapid reaction of the invented device permits makingcorrections in "real time", for example, during a laser shot duringlaser treatment of the human eye.

Naturally, simple remote control is also possible. Furthermore, thesolely electrical operation and control of the invented device permits,for example, an electronic "transmission" of the movements of thecontrol stick.

An advantageous embodiment of a control stick includes a permanentmagnet arranged in a movable manner via magnetic field plates. However,other embodiments are, of course, also possible as they are employedwith so-called "joy sticks", as long as they permit the translation of ashift or a movement of the stick in a plane into "homing signals" forthe coils.

A further advantage of the invented device is that the "solelyelectronic control" of beam movement permits, for example, connecting,in a simple manner, a recorder printer or a storage unit with which themanipulation of beam can be recorded, which may be, for example,important in ophthalmology in the event of liability claims, etc.

In any case, the invented device is particularly suitable formanipulating a laser beam in an eye examination or eye treatmentapparatus. For the working manner of the invented device it makes nodifference whether the laser is an argon laser for retina treatment, aneodymium YAG laser for cutting in the front eye media or an excimer or3<m-laser for keratotomy.

A BRIEF DESCRIPTION OF THE DRAWING

The present invention is made more apparent in the following usingpreferred embodiments in connection with the drawing, which expresslyrefers to all the details not disclosed in the text, depicting:

FIGS. 1a and b two preferred embodiments of biasing arrangements of aninvented device, and

FIG. 2 a preferred embodiment of a control stick.

PRESENTATION OF A PREFERRED EMBODIMENT

FIGS. 1a and 1b shows two preferred embodiments, which differessentially in the construction of the bias device, which defines thehome position. Both embodiments are provided with a tilting/rotatingjoint 1, to which two holders 2 are fixed, of which only one is depictedin the figures herein, for a mirror 3. Between both holders 2 runs abeam of light and, in particular, a laser beam 4, which is deflected bymirror 3 and whose point of impact is to be manipulated in a plane ofimpact 5, which is only depicted schematically. The only schematicallydepicted tilting/rotating joint is constructed in such a manner that itis provided with a channel of passage for the laser beam.

Joint 1 can be moved in the direction of the arrow so as to effecttilting about one axis 6 and the arrow 7 so as to effect rotationalmovement about another mutually perpendicular axis so that the mirror 3moves the direction of the arrows 6' and 6' and beam 4 is moved in theplane 5 in x/y direction.

A coil/magnet unit has been provided to move the tilting/rotating joint1 so as to effect tilting movement in the direction of arrow 6, whichshall be made more apparent in the following referring to FIG. 1b. Anidentical unit has been provided to move joint 1 to effect rotationalmovement in the direction of arrow 7 referring to FIG. 1a.

To joint 1 are fixed, by means of rods 8, permanent magnets 9, which arein a B-field, created by current-carrying coils 10. Said coils 10 areeach connected to another in such a manner that a flow of currentgenerates energy in one direction attracting one of the permanentmagnets 9 and repelling the other. By controlling the flow of thecurrent and its direction, a defined tilting/rotational movement ofjoint 1 can be produced and thereby a defined movement of mirror 3.Furthermore, a bias device has been provided, which defines the homeposition of joint 1 when coils 10 are not charged and thereby the homeposition of mirror 3. In the preferred embodiment depicted in FIG. 1a,the bias device is composed of two springs 11 and in the preferredembodiment according to FIG. 1b of two more permanent magnets 12, whichexercise an "equidirectional" force on magnets 9.

FIG. 2 shows a preferred embodiment of a control stick for the manualcontrol of the invented device. The control stick is provided with aknob 20, a ball seat 21, which permits moving said knob inx/y-direction, and a magnet 22, which is connected to ball seat 21.Moreover, magnetic field plates 23 have been provided, for thearrangement and circuit of which the figure is to be referred to. Eachpair of magnetic field plates 23 is connected to a coil configuration 10of the invented device by means of an intermediate amplifier, which isnot depicted in the figure. Moving said knob 20 in the x/y plane and thethus resulting shifting of the magnets changes the current flowingthrough the magnetic field plates and thus through coils 9 in proportionto the movement. The mirror is then tilted and rotated correspondinglyto manipulate the beam.

In the preceeding the present invention has been described usingpreferred embodiments without the intention of limiting the scope of thegeneral inventive idea as is set forth in the claims herein.

For example, it is possible to employ a device according to FIG. 1a torotate joint 1 in one direction about a vertical axis to effect mirrorand laser beam movement in the X plane and a device according to FIG. 1bto tilt it in the other direction about a horizontal axis to effectmirror and laser beam movement in the Y plane. Other control sticksconstructed in a different manner may be used instead of the controlstick depicted in FIG. 2. Instead of manual control, it is also possibleto use program control or automatic control, by way of illustration, animage processing device.

Furthermore, when employing a manual control, the "transmission" betweenthe movement of the control stick and the direction of the laser beammay be changed, for example, by changing the amplification factor of theintermediate amplifier.

If necessary, the coils and the permanent magnets may be exchanged, thusthe coils are arranged at joint 1 without changing the function of theinvented device.

When the invented device is employed in a laser with a slit lampapparatus, it is, for example, when guiding the beam through themicroscope arm, particularly advantageous if one of the mirrors in themicroscope arm is tilted by the invented device.

What I claim is:
 1. A device for steady-state adjustment of a light beamenabling laser treatment in an impact plane comprising joint meansenabling rotational movement about one axis and tilting movement aboutanother axis extending perpendicularly to the one axis, biasing meansfor biasing the joint means to a predetermined position, a mirrormounted on the joint means, first and second magnet-coil meansseparately mounted on the joint means for respectively enabling tiltingmovement of the joint means and the mirror about the one axis androtational movement of the joint means and the mirror about the anotheraxis independent of each other, and control means for controllingcurrent flow in coils of the first and second magnet-coil means toeffect movement of the joint means and the mirror, whereby the mirror isadjusted to enable deflection of a light beam to an impact point in theimpact plane.
 2. A device according to claim 1, wherein each of saidfirst and second magnet-coil means comprises two magnets and twoassociated coils disposed at opposite sides of the joint means at equaldistances from the joint means.
 3. A device according to claim 2,wherein the two associated coils of each of said first and secondmagnet-coil means are connected in series.
 4. A device according to oneof claims 1, 2 or 3 wherein the control means enable flow of currentthrough the coils in reversible directions.
 5. A device according toclaims 1, 2 or 3, wherein the biasing means comprises springs forbiasing the joint means to the predetermined position.
 6. A deviceaccording to one of claims 1, 2 and 3, wherein the biasing meanscomprises springs associated with the first and second magnet-coil meansfor biasing the joint means to the predetermined position.
 7. A deviceaccording to one of claims 1, 2 or 3, wherein the biasing meanscomprises permanent magnet means associated with the coil-magnet meansfor biasing the joint means to the predetermined position.
 8. A deviceaccording to claim 7, wherein the control knob is movable about axescorresponding to the one and another axes so that movement of thecontrol knob effects a corresponding displacement of the light beam inthe impact plane.
 9. A device according to claim 10, wherein the controlmeans includes field plates connected with the coils of the first andsecond magnet-coil means, and a permanent magnet displaceably mountedwith respect to the field plates, the permanent magnet being connectedto the control knob, and the field plates being responsive to themovement of the permanent magnet as effected by the control knob forcontrolling current flow through the coils of the first and secondmagnet-coil means in accordance therewith.
 10. A device according to oneof claims 1, 2 or 3, wherein the control means includes a control knobfor controlling current flow through the first and second magnet-coilmeans in accordance with the position thereof.
 11. A device according toclaim 8, wherein the control means includes field plates connected withthe coils of the first and second magnet-coil means, and a permanentmagnet displaceably mounted with respect to the field plates, thepermanent magnet being connected to the control knob, and the fieldplates being responsive to the movement of the permanent magnet aseffected by the control knob for controlling current flow through thecoils of the first and second magnet-coil means in accordance therewith.